Background

Clusterin (CLU, apolipoprotein J) is a multifunctional glycoprotein that is expressed ubiquitously in most tissues. Clusterin functions as a secreted chaperone protein that interacts with and stabilizes stress-induced proteins to prevent their precipitation (1,2). Research studies show that clusterin plays a protective role in Alzheimer’s disease by sequestering amyloid β(1-40) peptides to form long-lived, stable complexes, which prevents amyloid fibril formation (3-5).

In addition to the secreted protein, several intracellular isoforms are localized to the nucleus, mitochondria, cytoplasm, and ER. The subcellular distribution of these multiple isoforms leads to the diversity of clusterin functions. Additional studies report that clusterin is involved in membrane recycling, cell adhesion, cell proliferation, apoptosis, and tumor survival (6-9). The clusterin precursor is post-translationally cleaved into the mature clusterin α and clusterin β forms. Clusterin α and β chains create a heterodimer through formation of disulfide bonds (10).